U.S. homeland security officials said Friday they are confident Russia's government is behind recent hacks of American political organizations' email systems.

"These thefts and disclosures are intended to interfere with the US election process. Such activity is not new to Moscow," said the statement from the Department of Homeland Security and the office of the Director of National Intelligence on Election Security.

The statement says that "only Russia's senior-most officials could have authorized" hacks that resulted in documents posted on sites like WikiLeaks and DCLeaks.com, given "the scope and sensitivity of these efforts." But it stopped short of saying the Russian Government was responsible for the recent scanning and probing of American states' election systems.

Thousands of hacked Democratic National Committee emails were posted online this summer, upending the party's primary and convention, as the emails appeared to show some officials throwing their support behind Hillary Clinton over Bernie Sanders. Party Chairwoman Debbie Wasserman-Schultz eventually resigned over the uproar.

Congressman Adam Schiff, the ranking Democrat on the House Intelligence Committe, applauded the Obama administration's statement.

"All of us should be gravely concerned when a foreign power like Russia seeks to undermine our democratic institutions, and we must do everything in our power to guard against it," he said in a statement Friday.